1. Field of the Invention
The present invention relates to a reciprocating compressor, and more particularly, to a two stage reciprocating compressor which may be provided in a refrigerator having two evaporators for minimizing vibration and noise generated from the compressor resulting from the vibration generated from two compressing units by implementing one compressor having the two compressing units, and a refrigerator having the same.
2. Description of the Related Art
Generally, compressors convert electric energy into kinetic energy so as to compress a refrigerant by using the kinetic energy. The compressor is a core element of a freezing cycle system, and there are various types of compressors that compress the refrigerant, such as a rotary compressor, a scroll compressor, a reciprocating compressor, and so on.
FIG. 1 is a cross-sectional view of a conventional reciprocating compressor. As shown, the reciprocating compressor includes a casing 100 having a gas suction pipe 110 and a discharge pipe 120, a frame unit 200 disposed in the casing 100, a reciprocating motor 300 mounted at the frame unit 200 so as to generate a linear reciprocating driving force, a compressing unit 400 compressing gas by receiving the driving force from the reciprocating motor 300, and a resonance spring unit 500 for generating resonance by using the driving force of the reciprocating motor 300.
The frame unit 200 includes a front frame 210 supporting one side of the reciprocating motor 300, a middle frame 220 supporting another side of the reciprocating motor 300, and a rear frame 230 coupled to the middle frame 220 so as to form a space with the middle frame 220.
The reciprocating motor 300 includes an outer stator 310 fixed between the middle frame 220 and the rear frame 230, an inner stator 320 inserted into the outer stator 310 so as to be fixedly-coupled to a side of the front frame 210, a mover 330 movably inserted between the outer stator 310 and the inner stator 320, and a winding coil 340 coupled to the inside of the outer stator 310. The mover 330 includes a magnet 331 and a magnet holder 332 supporting the magnet 331.
The compressing unit 400 includes a cylinder 410 fixedly-coupled to the front frame 210, a piston 420 having one side movably inserted into the cylinder 410 and another side fixedly-coupled to the mover 330, a discharge valve assembly 430 mounted at one side of the cylinder 410 so as to control the discharge of the refrigerant, and a suction valve 440 mounted at an end portion of the piston 420 so as to control a flow of the refrigerant that is sucked into an inner space of the cylinder 410.
The piston 420 includes a cylindrical body 421 which has specific length and outer diameter, a flange 422 extended from the end of the cylindrical body in a vertical direction so as to be coupled to the magnet holder 332 of the mover, and a suction passage 423 penetratingly formed in the cylindrical body 421.
The discharge valve assembly 430 includes a discharge cover 431 for covering the inner space of the cylinder 410, a discharge valve 432 inserted into the discharge cover 431 so as to open/close the inner space of the cylinder 410, and a discharge spring 433 inserted into the discharge cover 431 so as to elastically support the discharge valve 432.
The resonance spring unit 500 includes a spring support 510 fixedly-coupled with the piston 420 and the mover 330, a front coil spring 520 coupled between the spring support 510 and the middle frame 220, and a rear coil spring 530 coupled between the spring support 510 and the rear frame 230.
Reference numeral 10 denotes a support spring, and 411 denotes the inner space of the cylinder.
An operation of the reciprocating compressor will be described as follows.
When power is supplied to the reciprocating compressor, the linear reciprocating driving force is generated by an electromagnetic interaction of the reciprocating motor 300, and the linear reciprocating driving force is transferred to the piston 420 through the mover 330.
The piston 420 is linearly reciprocated in the inner space 411 of the cylinder by receiving the linear reciprocating driving force of the mover 330. By the linear reciprocating motion of the piston 420, the suction valve 440 and the discharge valve 432 are operated by a difference between a pressure of the inner space 411 and an external pressure of the cylinder. The refrigerant is sucked and compressed so as to be discharged into the inner space 411 of the cylinder. The discharged refrigerant flows outside of the compressor through the discharge cover 431 and the discharge pipe 120. This procedure is repeated so that the refrigerant is compressed.
The front coil spring 520 and the rear coil spring 530 are contracted/relaxed together with the reciprocating motion of the mover 330 and the piston 420, thereby elastically supporting the mover 330 and the piston 420 and causing the resonance.
The reciprocating compressor may be provided in a freezing cycle apparatus and the freezing cycle apparatus may be provided in a refrigerator.
Refrigerators may be categorized as a type having one evaporator (cooling unit) or another type having two evaporators.
In a refrigerator having two evaporators, i.e., a freezing chamber evaporator and a refrigerating chamber evaporator, the temperature of the freezing chamber and the refrigerating chamber is accurately controlled so that it is possible to store foods in fresh state for a long time. However, in a refrigerator having two evaporators and one compressor, the freezing chamber and the refrigerating chamber should be alternately operated. Further, in a refrigerator having two evaporators and two compressors, a large space for a machine chamber for installing the compressors is required, such that the space for storing the foods is smaller.
Meanwhile, when the reciprocating compressor having one compressing unit is applied to a refrigerator having two evaporators, two reciprocating compressors must be mounted in the refrigerator. Accordingly, the space for the machine chamber where the compressor is installed is enlarged, and the storing space of the refrigerator is smaller.